/*
 * Copyright (c) 2017, 2017, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package com.oracle.svm.core.posix;

import org.graalvm.nativeimage.c.type.CCharPointer;
import org.graalvm.nativeimage.c.type.CTypeConversion;
import org.graalvm.nativeimage.c.type.CTypeConversion.CCharPointerHolder;
import org.graalvm.word.WordFactory;

import com.oracle.svm.core.CompilerCommandPlugin;
import com.oracle.svm.core.posix.headers.LibC;
import com.oracle.svm.core.posix.headers.Stdlib;

public abstract class PosixExecutableName implements CompilerCommandPlugin {

    /** The platform-independent key for getting the executable name. */
    public static String getKey() {
        return "com.oracle.svm.core.posix.GetExecutableName";
    }

    @Override
    public String name() {
        return PosixExecutableName.getKey();
    }

    /** A platform-independent method to canonicalize a path. */
    protected String realpath(String path) {
        /*
         * Find the real path to the executable. realpath(3) mallocs a result buffer and returns a
         * pointer to it, so I have to free it.
         */
        try (CCharPointerHolder pathHolder = CTypeConversion.toCString(path)) {
            final CCharPointer realpathPointer = Stdlib.realpath(pathHolder.get(), WordFactory.nullPointer());
            if (realpathPointer.isNull()) {
                /* Failure to find a real path. */
                return null;
            } else {
                /* Success */
                final String result = CTypeConversion.toJavaString(realpathPointer);
                LibC.free(realpathPointer);
                return result;
            }
        }
    }
}
